docs: def _build_process_type_list(self):
          """Generates lists of processes organized by process type.
  
          Following object attributes are generated or updated:
  
          :ivar dict process_types:   a dictionary with entries:
                                      ``'diagnostic'``, ``'explicit'``,
                                      ``'implicit'`` and ``'adjustment'`` which
                                      point to a list of processes according to
                                      the process types.
  
          The ``process_types`` dictionary is created while walking
          through the processes with :func:`~climlab.utils.walk.walk_processes`
  
          CHANGING THIS TO REFER ONLY TO THE CURRENT LEVEL IN SUBPROCESS TREE
  
          """
          self.process_types = {'diagnostic': [], 'explicit': [], 'implicit': [], 'adjustment': []}
          #for name, proc, level in walk.walk_processes(self, topdown=self.topdown):
          #    self.process_types[proc.time_type].append(proc)
          for name, proc in self.subprocess.items():
              self.process_types[proc.time_type].append(proc)
          self.has_process_type_list = True